Oxidative stress during rehabilitation from protein malnutrition associated with aerobic exercise in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Metabolismo glicídico em ratos submetidos a desnervação do músculo esquelético e ao exercício de natação

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A influência do ultrassom e do treinamento físico sobre os triglicérides séricos e intramusculares em ratos diabéticos experimentais

O ultrassom terapêutico é visto hoje como um dos recursos mais utilizados na prática da medicina clínica e o exercício físico é consolidado como uma terapêutica eficaz e eficiente em diversos casos, porém ainda pouco investigados em conjunto; por isso, o presente trabalho tem como objetivo analisar a influência do ultrassom e do exercício físico sobre as concentrações de triglicérides sérico e intramusculares (IMTG) em ratos diabéticos experimentais. Foram utilizados ratos Wistar adultos divididos em oitos grupos: Diabéticos Sedentários (DS), Diabéticos Treinados (DT), Diabéticos Sedentários e Ultrassom (DSUs), Diabéticos Treinados e Ultrassom (DTUs), Controle Sedentário (CS), Controle Treinado (CT), Controle Sedentário e Ultrassom (CSUs), Controle Treinado e Ultrassom (CTUs). O protocolo de treinamento constituía de natação cinco dias por semana, 30 minutos, por dia com uma carga máxima equivalente a 8% da massa corporal, durante três semanas. A terapia ultrassônica foi realizada cinco dias por semana, durante duas semanas, com intensidade de 0,2W/cm² e frequência de 1,0MHz. Não houve diferenças significativas nos triglicerídeos séricos e nos músculo Tibial Anterior e Gastrocnêmio. Para o músculo Sóleo as concentrações dos grupos diabéticos foram menores comparados com as dos grupos controles e também entre os grupos DT e DTUs comparado com DS e DSUS, sendo que treinados apresentaram as menores concentrações. O ultrassom pulsado na intensidade proposta não influenciou as concentrações séricas de triglicerídeos nem de IMTG. Porém o exercício físico foi eficaz em reduzir IMTG no músculo Sóleo.

Efeito do exercício físico contínuo e intervalado no peso e perfil bioquímico de ratas Wistar prenhes e consequências no peso da prole

INTRODUÇÃO: A prática de atividade física é reconhecida como fator importante para a preservação, recuperação e manutenção da saúde. O estímulo à prática de exercícios é crescente, mas quando relacionado à gravidez, dúvidas surgem sobre os efeitos deletérios ou salutares na mãe e no feto. OBJETIVO: O objetivo deste trabalho foi avaliar os efeitos do exercício físico intervalado e contínuo no perfil bioquímico de ratas Wistar prenhes e avaliar o efeito destes exercícios no peso da placenta e dos filhotes. MÉTODOS: Utilizou-se 45 ratas Wistar divididas em grupos de 15 animais segundo o tipo de exercício: controle (GC), exercício contínuo (GCO) e exercício intermitente (GIN). Os exercícios constituíram-se de natação forçada, cinco dias por semana, em piscinas individuais: exercício contínuo (duração de 45 minutos diários com sobrecarga de 5% do peso corporal) e intermitente (45 minutos com estímulos de 15 segundos de exercício e 15 de repouso com sobrecarga de 15% do peso corporal). O exercício foi praticado do primeiro ao 20º dia de prenhez. Após este período avaliou-se o peso e os níveis de glicemia, colesterol total, LDL-C, HDL-C e triglicérides das ratas, assim como o peso da placenta e dos filhotes. RESULTADOS: Não se observou modificação no peso das mães. Houve redução significativa nos níveis de LDL-C. O peso das placentas não variou, mas os pesos dos filhotes variaram estatisticamente entre os três grupos (4,153 ± 0,649; 3,682 ± 0,070 e 3,453 ± 0,052, respectivamente, para os filhos de mães do GC, GIN e GCO). CONCLUSÕES: Conclui-se que a prática do exercício físico contínuo e intermitente por ratas prenhes, neste modelo experimental, não interferiu no peso corpóreo das mesmas, mas interferiu no peso dos filhotes ao nascer

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 ± 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 ± 16 and 36 ± 12%, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40%) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 ± 14 vs 14 ± 5 cmH2O, and 87 ± 30 vs 34 ± 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 ± 0.7 vs 2.3 ± 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

Protocols for hyperlactatemia induction in the lactate minimum test adapted to swimming rats

The lactate minimum test (LACmin) has been considered an important indicator of endurance exercise capacity and a single session protocol can predict the maximal steady state lactate (MLSS). The objective of this study was to determine the best swimming protocol to induce hyperlactatemia in order to assure the LACmin in rats (Rattus norvegicus), standardized to four different protocols (P) of lactate elevation. The protocols were PI: 6 min of intermittent jumping exercise in water (load of 50% of the body weight - bw); P2: two 13% bw load swimming bouts until exhaustion (thin); P3: one thin 13% bw load swimming bout; and P4: two 13% bw load swimming bouts (1st 30 s, 2nd to thin), separated by a 30 s interval. The incremental phase of LACmin beginning with initial loads of 4% bw, increased in 0.5% at each 5 min. Peak lactate concentration was collected after 5, 7 and 9 min (mmol L-1) and differed among the protocols P 1 (15.2 +/- 0.4, 14.9 +/- 0.7, 14.8 +/- 0.6) and P2 (14.0 +/- 0.4, 14.9 +/- 0.4, 15.5 +/- 0.5) compared to P3 (5.1 +/- 0.1, 5.6 +/- 0.3, 5.6 +/- 0.3) and P4 (4.7 +/- 0.2, 6.8 +/- 0.2, 7.1 +/- 0.2). The LACmin determination success rates were 58%, 55%, 80% and 91% in P1, P2, P3 and P4 protocols, respectively. The MLSS did not differ from LACmin in any protocol. The LACmin obtained from P4 protocol showed better assurance for the MLSS identification in most of the tested rats. (c) 2007 Elsevier B.V. All rights reserved.

Effects of nandrolone decanoate on the neuromuscular junction of rats submitted to swimming

This study addressed the effects of nandrolone decanoate (ND) on contractile properties and muscle fiber characteristics of rats submitted to swimming. Male Wistar rats were grouped in sedentary (S), swimming (Sw), sedentary+ND (SND), and swimming+ND (SwND), six animals per group. ND (3 mg/kg) was injected (subcutaneously) 5 days/week, for 4 weeks. Swimming consisted of 60-min sessions (load 2%), 5 days/week, for 4 weeks. After this period, the sciatic nerve extensor digitorum longus (EDL) muscle was isolated for myographic recordings. Fatigue resistance was assessed by the percent (%) decline of 180 direct tetanic contractions (30 Hz). Safety margin of synaptic transmission was determined from the resistance to the blockade of indirectly evoked twitches (0.5 Hz) induced by pancuronium (5 to 9 x 10(-7) M). EDL muscles were also submitted to histological and histochemical analysis (haematoxylin-eosin (HE); nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR)). Significant differences were detected by two-way ANOVA (p<0.05). ND did not change body mass, fatigue resistance or kinetic properties of indirect twitches in either sedentary or swimming rats. In contrast, ND reduced the safety margin of synaptic transmission in sedentary animals (SND=53.3+/-4.7% vs. S=75.7+/-2.0%), but did not affect the safety margin in the swimming rats (SwND=75.81+/-3.1% vs. Sw=71.0+/-4.0%). No significant difference in fiber type proportions or diameters was observed in EDL muscle of any experimental group. These results indicate that ND does not act as an ergogenic reinforcement in rats submitted to 4 weeks of swimming. on the other hand, this study revealed an important toxic effect of ND, that it reduces the safety margin of synaptic transmission in sedentary animals. Such an effect is masked when associated with physical exercise. (C) 2004 Elsevier B.V. All rights reserved.

Effect of exercise mode on the blood lactate removal during recovery of high-intensity exercise

The aim of this study was to determine the effect of exercise mode on the blood lactate removal during recovery of high-intensity exercise. Nine male individuals performed the following tests in order to determine the blood lactate removal: Running - 2x200 m, the subjects ran at their maximum capacity, and rested 2 min between each bout. Swimming - 2x50 m, the subjects swam at their maximum capacity, and rested 2 min between each bout. Each test was realized on different days with three recovery modes: passive (sitting down), swimming, or running. Recovery exercise intensity was corresponding to the aerobic threshold. All recovery activities lasted 30 min. The two forms of active recovery were initiated 2 min after the end of high-intensity exercise and lasted 15 min, and were followed by 13 min of seated rest. After 1,7, 12,17, and 30 min of the end of high-intensity exercise, blood samples (25 mu l) were collected in order to determine the blood lactate concentration. By linear regression, between the logarithm of lactate concentration and its respective time of recovery, the half-time of blood lactate removal (t1/2) was determined. Time of high-intensity exercise and the lactate concentration obtained in the 1(st) min of recovery were not different between running and swimming. Passive recovery (PR) following running (R-PR=25.5+/-4.3 min) showed a t1/2 significantly higher than PR after swimming (S-PR=18.6+/-4.3 min). The t1/2 of the sequences running-running (R-R=13.0 min), running-swimming (R-S=12.9+/-3.8 min), swimming-swimming (S-S=13.2+/-2.8 min), and swimming-running (S-R=12.9+/-3.8 min) were significantly lower than the t1/2 of the R-PR and S-PR. There was no difference between the t1/2 of the sequences R-R R-S, and S-S. on the other hand the sequence S-R showed a t1/2 significantly lower than the sequences S-S and R-R. It was concluded that the two forms of active recovery determine an increase in the blood lactate removal, regardless of the mode of high-intensity exercise performed previously. Active recovery performed by the muscle groups that were not previously fatigued, can improve the blood lactate removal.

Impact of the training program on lipid profile and cardiac health

The aim of this study was to investigate the effects of training programs on serum lipid profile and myocardial oxidative stress. Male Wistar rats (2 mo-old) were divided into three groups (n=8): sedentary (S), loadless trained (T) and trained-overload 2% body weight (TL). T and TL were trained through swimming for 9 weeks. T and TL rats had increased myocardial lipoperoxide (TBA) and lipid hydroperoxide (HP), whereas HP was higher in TL than in T animals. Superoxide dismutase (SOD) activities were lowest in TL. Myocardial glutathione peroxidase (GSH-Px) was lower in TL than in T and S rats. TL decreased HDL-cholesterol and increased LDL-cholesterol. The serum lactate dehydrogenase and TBA were increased, while SOD and GSH-Px activities were decreased in TL rats. Loadless training was able to improve HDL-cholesterol and to reduce LDL-cholesterol. In conclusion, the loadless training program induced beneficial effects on lipid profile, while overload training induced dyslipidemic profile that was associated with serum oxidative stress. The overload training program was deleterious relative to loadless training program, increasing myocardial oxidative stress.

Non-exhaustive test for aerobic capacity determination in swimming rats

The aim of this study was to describe a double-bout exercise test for non-exhaustive aerobic capacity determination in swimming rats. Adult rats were Submitted to 4 swimming tests at different intensities (4%, 6%, 7%, and 8% of body mass), with intervals of 48 h between them. Two exercise bouts of equal intensity lasting 5 min were performed, separated by 2 min with blood collection for lactate analysis. For each intensity, delta lactate was determined by subtracting lactate concentration at the end of the first effort from the lactate at the end of the second effort. Individual linear interpolation of delta lactate concentration enabled determination of a null delta, equivalent to the critical load (CL). Maxima) lactate steady state (MLSS) was also determined. The estimated CL was of 4.8% body mass and the MLSS was observed at 100% of CL, with blood lactate of 5.20 mmol/L. At 90%, blood lactate stabilized, with a progressive increase to 110% CL. These results offer a potential determination of aerobic capacity in swimming rats.

Effects of soy protein and resistance exercise on body composition and blood lipids in postmenopausal women

Objective: To assess the effect of soy protein and progressive resistance training on body composition and lipids in postmenopausal women.Design: In a controlled trial, 46 postmenopausal women were randomized to one of four groups: 25 g of soy protein (SP, n = 10), 25 g of soy protein plus resistance exercise (SPE, n = 14), 25 g of maltodextrine (placebo) (PL, n = 11), or placebo plus resistance exercise (PLE, n = 11). Progressive resistance training was held three times a week for 16 weeks and included 8 exercises (3 series of 8-12 repetitions). At baseline and after 16 weeks, body mass index, waist circumference (WC), body fat, muscle mass and serum lipid levels were measured. To confirm isoflavone absorption, urinary concentrations were determined. The t-test of Student and ANOVA were used in the statistical analysis.Results: Subjects were classified as overweight and showed android fat distribution: Urinary isoflavone excretion indicated compliance to soy protein treatment. After 16 weeks of intervention, both SPE and PLE groups showed a significant increase of 1.3 kg in muscle mass and reduction in WC of -1.4 and -2.1 cm, respectively (p < 0.05). Significant decreases in the mean values of total cholesterol and LDL (-29.0 and -24.0 mg/dL, p < 0.001 and p < 0.006, respectively) were observed in the users of soy protein alone (SP).Conclusions: Soy protein supplementation did not influence the indicators of body composition. However, it exerted possible favorable effects on lipid profile in postmenopausal women. The increase in muscle mass and reduction in abdominal fat were correlated with resistance training. (c) 2006 Elsevier B.V.. All rights reserved.

EFFECT OF CAFFEINE ON THE METABOLISM OF RATS EXERCISING BY SWIMMING

Several studies have demonstrated that caffeine improves endurance exercise performance but the mechanisms are not fully understood. Possibilities include increased free fatty acid (FFA) oxidation with consequent sparing of muscle glycogen as well as enhancement of neuromuscular function during exercise. The present study was designed to investigate the effects of caffeine on liver and muscle glycogen of 3-month old, male Wistar rats (250-300 g) exercising by swimming. Caffeine (5 mg/kg) dissolved in saline (CAF) or 0.9% sodium chloride (SAL) was administered by oral intubation (1 mu l/g) to fed rats 60 min before exercise. The rats (N = and-IO per group) swam bearing a load corresponding to 5% body weight for 30 or 60 min. FFA levels were significantly elevated to 0.475 +/- 0.10 mEq/l in CAF compared to 0.369 +/- 0.06 mEq/l in SAL rats at the beginning of exercise. During exercise, a significant difference in FFA levels between CAF and SAL rats was observed at 30 min (0.325 +/- 0.06 vs 0.274 +/- 0.05 mEq/l) but not at 60 min (0.424 +/- 0.13 vs 0.385 +/- 0.10 mEq/l). Blood glucose showed an increase due to caffeine only at the end of exercise (CAF = 142.1 +/- 27.4 and SAL = 120.2 +/- 12.9 mg/100 ml). No significant difference in liver or muscle glycogen was observed in CAF as compared to SAL rats, at rest or during exercise. Caffeine increased blood lactate only at the beginning of exercise (CAF = 2.13 +/- 0.2 and SAL = 1.78 +/- 0.2 mmol/l). These data indicate that caffeine (5 mg/kg) has no glycogen-sparing effect on rats exercising by swimming even though the FFA levels of CAF rats were significantly higher at the beginning of exercise.